Vessel implant for the treatment of an aneurysm

ABSTRACT

The invention relates to a vessel implant for the treatment of an aneurysm, i.e. a dilatation of the cross-sectional area of a blood vessel, comprising an elongate body which has an inlet opening, an outlet opening and a passage connecting the inlet opening to the outlet opening for blood flowing through the blood vessel, with the passage being bounded in the peripheral direction by a blood-impermeable wall, and with the inlet opening having a larger cross-sectional area than the outlet opening.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application Number 102007 019 058.3, filed Apr. 23, 2007, which is hereby incorporated byreference as if set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vessel implant for the treatment ofan aneurysm, comprising an elongate body which has an inlet opening, anoutlet opening as well as a passage connecting the inlet opening withthe outlet opening for blood flowing through the blood vessel, with thepassage being bounded in the peripheral direction by a blood-impermeablewall.

An aneurysm is a pathological, spatially restricted dilatation, swellingor expansion of a flood vessel, in particular of an artery. Aneurysmscan occur at any section of an artery. Abdominal aortic aneurysms oraneurysms at the popliteal artery occur particularly frequently. Dilatedblood vessels are subject to a high risk of rupture so that there is arisk of fatal bleeding. Furthermore, dilated blood vessels tend tobecome larger. The risk of rupture increases as the diameter of theaneurysm increases since the pressure exerted on the vessel wall of theblood vessel by the blood flowing through the blood vessel increases asthe vessel width increases (Bernoulli's Law).

2. The Prior Art

It is known to treat such dilated blood vessels using tubular orhose-shaped implants which are also called stents. In this connection, astent having a blood-impermeable wall is inserted into the affectedblood vessel such that the aneurysm can be bridged by means of thestent. In this connection, the two ends of the stent are fixed in asshape matched a manner as possible at the non-dilated regions of theblood vessel adjoining the dilated region at both sides, whereby a sealof the dilatation should be achieved to prevent blood from continuing toflow into the dilatation. The diameter of such a stent approximatelycorresponds to the normal diameter of a vessel.

There is, however, the problem with these solutions that small leaks canfrequently occur, due to insufficient adaptation to the vessel, betweenthe stent and that region of the vessel wall of the blood vessel atwhich the stent is fixed. Blood can continue to flow into the aneurysm,in particular due to leaks present at the inlet opening side or due tocollateral vessels so that the risk of rupture of the vessel wall in theregion of the aneurysm is not eliminated.

It is therefore the underlying object of the invention to provide avessel implant of the initially named kind which reduces the risk of arupture of the vessel wall in the region of an aneurysm.

This object is satisfied by a vessel implant having the features ofclaim 1 and in particular in that the inlet opening has a largercross-sectional area than the outlet opening.

BRIEF DESCRIPTION OF THE INVENTION

The vessel implant is preferably fixed at its end having the inletopening and/or at a section directly adjoining the inlet opening to thenon-dilated region of the blood vessel disposed upstream of theaneurysm. The vessel implant preferably has a length which can extendover the total length of the aneurysm.

In accordance with the continuity law for non-compressible fluids, thesame blood volume exits the outlet opening of the body that has flowninto the body at the inlet opening of the body, i.e. the volume flow orthe volume moving through a cross-section of the body within a unit oftime is the same at the inlet opening and at the outlet opening. Itresults from this that the blood flowing through the blood vessel andthus through the body passes through the outlet opening at a higherspeed than through the inlet opening. An underpressure by which theblood located in an aneurysm is sucked out arises at the end of the bodyhaving the outlet opening—as with a water jet pump—due to the higherspeed. In this way, a corresponding underpressure also arises inside theaneurysm so that the dilated vessel wall is relieved.

This effect even occurs when the vessel implant is not completely sealedat the inlet opening side. The risk of a rupture of the vessel wall ofthe aneurysm can thus be effectively reduced using the vessel implantmade in accordance with the invention.

Since a seal of the aneurysm at the downstream side by the vesselimplant is not required and does not even have to be 100% upstream ofthe seal, the vessel implant can also be used in those cases in which asealing fixing at the blood vessel is not possible upstream and/ordownstream of the aneurysm. Since a seal is not necessary downstream ofthe aneurysm, the vessel implant in accordance with the invention canalso be used with an abdominal aortic aneurysm which starts directly atthe branch to the two femoral arteries. A fixation downstream of theaneurysm can either be dispensed with or a blood-permeable fixation canbe used. For an abdominal aortic aneurysm starting directly at thebranches to the two renal arteries, the vessel implant can be providedwith a fixation section which in particular adjoins the inlet opening ofthe body directly and which is made blood-permeable in order not toclose the branches to the renal arteries.

In accordance with an embodiment of the invention, the body, a sectionof the body located between the inlet opening and the outlet openingand/or the passage from the inlet opening to the outlet openingconverges and/or converge. A gradual reduction of the cross-sectionalarea from the inlet opening to the outlet opening can hereby be achievedover the total length of the body to avoid turbulence in the blood flow,for example. The convergence is preferably made uniformly, continuouslyand/or conically.

The body is preferably made for contact at the vessel wall of the bloodvessel in the region of the inlet opening and/or at a section of thebody adjoining the inlet opening. The outer cross-sectional area of thebody is in particular dimensioned in the region of the inlet openingand/or of the section adjoining the inlet opening such that the bodycontacts the vessel wall of the blood vessel in the region of the inletopening and/or at the section adjoining the inlet opening in theimplanted state. A fixation of the body in the blood vessel can herebybe achieved.

To achieve a particularly good fixation of the vessel implant in theblood vessel, it can be advantageous for the section of the bodyadjoining the inlet opening to be cylindrical. The body can thus beadapted to the internal diameter of the blood vessel over a largerregion.

It is particularly preferred for the section of the body adjoining theinlet opening to have a wall made permeable to blood. The sectionadjoining the inlet opening can be made as a mesh, for example. Aningrowth of the cells of the vessel wall of the blood vessel into thebody of the implant is hereby promoted and thus a particularly firmfixation achieved.

In accordance with a further embodiment of the invention, the outerdimension of the body is dimensioned in the region of the outlet openingsuch that the body is spaced apart from the vessel wall of the bloodvessel in the region of the outlet opening. This can in particular bethe case when the outer dimension of the body also converges toward theside having the outlet opening in addition to the cross-sectional areaof the passage.

The body is preferably provided with blood-permeable fixation means forthe end of the body at the outlet opening side, said means being madefor contact with the vessel wall of the blood vessel. A lateralmigration of the end of the body having the outlet opening to and fro inthe blood flow can hereby be prevented so that a radial fixation isachieved within the blood vessel. The fixing means are madeblood-permeable to impede a sucking of the blood out of the aneurysmeffected by the generated underpressure as little as possible.

The fixing means can be made to keep the body spaced apart from thevessel wall of the blood vessel in the region of the outlet opening. Itis hereby ensured that the end of the body having the outlet openingdoes not contact the vessel wall of the blood vessel so that thepreviously explained water jet pump effect can occur over the fullperipheral area around the outlet opening. The fixing means can inparticular be made such that the outlet opening or the end of the bodyhaving the outlet opening is held in centered form inside the bloodvessel.

In accordance with a further embodiment of the invention, the fixingmeans are provided in the region of the outlet opening at the body.

The fixing means can be made as a mesh, as a plurality of fixingelements respectively projecting from the body with a radial componentand/or as a conical stent.

The body or a part thereof can be made in one piece with the fixingmeans. The fixing means can, however, also be made as a separate part oras separate parts which is/are connected to the body or to a partthereof.

The wall of the body can be rigid, flexible or partly rigid andflexible. The wall can, for example, be a mesh in the form of a stentwhich is provided with a coating. The coating can be provided at theoutside, at the inside or both at the outside and at the inside of themesh. The wall is preferably made of biocompatible material. The meshcan, for example, be made as a self-expanding stent or as aballoon-expanding stent. Whereas the vessel implant in a rigidembodiment is inserted into the blood vessel surgically, for example, atransluminal implantation is possible with an embodiment which is atleast partly flexible.

The vessel implant, in particular the body or the wall of the body, canhave a multi-part structure. In this case, the individual parts can beintroduced into the blood vessel and/or deposited within the bloodvessel separately from one another. With a multi-part wall, for example,which includes a blood-impermeable envelope and a support structure forthe envelope, for example a mesh, the envelope can be introduced intothe blood vessel and/or deposited within the blood vessel separatelyfrom the support structure and/or separately from fixing means for thebody. On a separate introduction, for example disposed in series on acatheter or sequentially in each case with different catheters, theaccess for the catheter can be selected to be smaller so that the woundhealing is improved.

It is, for example, possible that first only the envelope is introducedand deposited, with said envelope preferably being held at an end by theintroduction instrument after the deposition. The support structure cansubsequently be inserted into the envelope so that on the expansion ofthe support structure, the envelope is also expanded at the same timeand is pressed through the support structure toward the vessel wall andis held there. If desired, the fixing means can be introduced in a nextstep and can be connected to the body formed by the support structureand the envelope.

The wall can also only include a blood-impermeable envelope, inparticular without a support structure. The envelope can then, forexample, be fastened to a section of the body adjoining the inletopening upstream, in particular separate from the envelope, or can bepressed by it against the vessel wall for fastening. In this case, thesupport structure preferably has a short length so that it only comes tolie upstream of the aneurysm or only projects into the aneurysm over anin particular very short part region.

The present invention further relates to a vessel implant, comprisingtwo bodies which are each made as explained above, with the bodies beingconnected to one another in the region of their inlet openings at abranch of the vessel implant. Such a vessel implant can, for example, beused with an abdominal aortic aneurysm in the region of the branch tothe two femoral arteries.

The two bodies can in particular have a common section adjoining thebranch for the contact with the vessel wall of the blood vessel.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Non-restricting embodiments of the invention are shown in the drawingsand will be described in the following. The drawings are shown,schematically in each case:

FIG. 1 a first embodiment of a vessel implant in accordance with theinvention;

FIG. 2 the vessel implant from FIG. 1 with fixing elements;

FIG. 3 the vessel implant from FIG. 1 with star-shaped fixing means;

FIG. 4 the vessel implant from FIG. 1 with fixing means made as aconical stent; and

FIG. 5 a further embodiment of a vessel implant in accordance with theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The vessel implant shown in FIG. 1 includes an elongate tubular body 11which is divided into a section 11-1 and a section 11-2. The section11-1 of the body 11 is conical and has a blood-impermeable wall 17. Inthe longitudinal direction, the section 1 1-1 is bounded by an inletopening 13 and an outlet opening 15 which are connected to one anotherby a conical passage 19 which is bounded by the wall 17 in the radialdirection. The second section 11-2 is cylindrical and directly adjoinsthe first section 11-1 of the body 11 at the inlet opening side. Thesecond section 11-2 is, however, optional and can also be omitted.

The inlet opening 13 has a larger cross-sectional area than the outletopening 15, i.e. the inner diameter or the lumen of the inlet opening 13is larger than the inner diameter or lumen of the outlet opening 15.

The vessel implant with the body 11 is inserted into a blood vessel 27which has a cross-sectional area dilatation 29, i.e. an aneurysm,locally. The body 11 contacts the vessel wall of the blood vessel 27with its cylindrical section 11-2 and in the region of the inlet opening13 in a region of the blood vessel not dilated, with the outer diameterof the cylindrical section 11-2 and the outer diameter in the region ofthe inlet opening 13 being selected to be slightly larger than the innerdiameter of the blood vessel 27 such that the cylindrical section 11-2of the body 11 contacts the vessel wall under tension, whereby a firmholding of the vessel implant is achieved. The section 11-2 is made as amesh to promote an ingrowth of the cells of the vessel wall of the bloodvessel 27.

The fixing of the cylindrical section 11-2 can take place in a mannerknown per se. The body 11 of the vessel implant can, for example, bemade as a self-expanding stent, in particular consisting of nitinol,which is introduced into the blood vessel 27 by means of a catheter in acompressed state and automatically expands into a state with a largerradius after deposition due to the blood temperature so that thecylindrical section 11-2 contacts the vessel wall. It is also possiblethat the body 11 of the vessel implant is made, for example, ofstainless steel or of spring steel and is in particular expanded via aballoon until the cylindrical section 11-2 comes into contact with thevessel wall.

The body 11 opens freely in the blood vessel 27 at the outlet openingside. The length of the body 11 is sufficient to completely span theaneurysm 29. It is, however, also generally also conceivable for theoutlet opening 15 of the body 11 to be located in the region of theaneurysm 29 as long as it is ensured that an underpressure is generatedinside the aneurysm 29 due to the described water jet pump effect.

Blood flowing through the blood vessel 27 in the direction of flow 31enters via the cylindrical section 11-2 and through the inlet opening 13into the conical section 11-1 of the body 11 and leaves it through theoutlet opening 15, with the flow rate increasing constantly within theconical section 11-2 due to the continuously narrowing passage 19.

Blood which passes between the vessel wall of the blood vessel 27 andthe conical section 11-1 of the body 11 comprising the blood-impermeablewall 17 in the region of the inlet opening 13 through a leak inaccordance with an arrow 33 and which collects in the aneurysm 29 isconveyed in the direction of flow 31 due to the water jet pump effectdescribed above by the blood flowing out of the outlet opening 15 at anincreased rate so that an underpressure arises inside the aneurysm 29and the build-up of too high a pressure onto the vessel wall of theblood vessel 27 in the region of the aneurysm 29 can be prevented. Thepressure difference occurring due to the underpressure between theaneurysm 29 and the region of the blood vessel 27 surrounding the outletopening 15 of the body 11 is illustrated by an arrow 35.

The vessel implant shown in FIG. 2 substantially corresponds to thevessel implant shown in FIG. 1. In contrast to FIG. 1, the vesselimplant in accordance with FIG. 2, however, has a conical stent 21 witha blood-permeable wall which converges in the same direction as theconical section 11-1 of the body 11. The conical stent 21 having alarger opening angle than the conical body section 11-1 is attached atits tapered end to the body 11 in the region of the outlet opening 15.The conical stent 21 is made as a fixing means and is supported at itsend points 23 remote from the body 11 at the vessel wall of the bloodvessel 27. The body 11 is hereby held spaced apart from the vessel wallof the blood vessel 27 in the region of the outlet opening 15 and in acentered fashion within the blood vessel 27.

The fixing means 21 shown in FIG. 2 are, however, only of an exemplarynature. Blood-permeable fixing means of any desired other form cangenerally be provided which can hold the end of the body II comprisingthe outlet opening 15 spaced apart from the vessel wall of the bloodvessel 27 and centered within the blood vessel 27. A plurality ofradially outwardly projecting fixing elements 21 can in particular beprovided. In FIG. 3, the fixing elements 21 are made, for example, inthe form of a star whose end points 23 remote from the body II arearranged on an imaginary circular line 25 which is dimensioned such thatthe end points 23 contact the vessel wall of the blood vessel 27. In thevessel implant shown in FIG. 4, the fixing means are made as ablood-permeable conical stent 21 which consists of a mesh so thatoverall a double truncated cone-shaped vessel implant is formed whichhas a restriction centrally. The fixing means 21 shown in FIGS. 2 to 4can each be made in one piece with the body 11 or can be connected tothe body 11 in the region of the outlet opening 15.

The vessel implant shown in FIG. 5 is made at least substantiallyY-shaped and includes two bodies 11 which are essentially as describedabove and which are each conical. The two bodies 11 are connected to oneanother in the region of their respective entry openings 13 at a branch37 of the vessel implant, with a common cylindrical section 11-2 beingprovided for the two bodies 11. The vessel implant in accordance withthis embodiment is in particular suitable to be used with an abdominalaortic aneurysm 27, with the cylindrical section 11-2 being fixedupstream of the aneurysm 29 in the abdominal aorta 27′ in the implantedstate and being largely sealed with respect to the vessel wall at leastin the transition region to the inlet openings 13 and with the outletopenings 15 of the two bodies 11 each ending in a fixed or unfixed statein a respective femoral artery 27″.

The following description of preferred embodiments of the invention isnot intended to limit the scope of the invention to these preferredembodiments, but rather to enable any person skilled in the art to makeand use the invention.

As any person skilled in the art will recognize from the previousdescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of the invention defined in the followingclaims.

1. A vessel implant for the treatment of an aneurysm, i.e. a dilatationof the cross-sectional area of a blood vessel, comprising an elongatebody which has an inlet opening, an outlet opening and a passageconnecting the inlet opening to the outlet opening for the blood flowingthrough the blood vessel, with the passage being bounded in theperipheral direction by a blood-impermeable wall, characterized in thatthe inlet opening has a larger cross-sectional area than the outletopening.
 2. A vessel implant in accordance with claim 1, characterizedin that the body, a section of the body located between the inletopening and the outlet opening and/or the passage converges/convergefrom the inlet opening toward the outlet opening.
 3. A vessel implant inaccordance with claim 2, characterized in that the convergence isuniform, continuous and/or conical.
 4. A vessel implant in accordancewith claim 1, characterized in that the body is designed for contactwith the vessel wall of the blood vessel in the region of the inletopening and/or at a section of the body adjoining the inlet opening. 5.A vessel implant in accordance with claim 4, characterized in that thesection of the body adjoining the inlet opening is cylindrical.
 6. Avessel implant in accordance with claim 4, characterized in that thesection of the body adjoining the inlet opening has a blood permeablewall.
 7. A vessel implant in accordance with claim 1, characterized inthat the outer dimension of the body is dimensioned in the region of theoutlet opening such that the body is spaced apart from the vessel wallof the blood vessel in the region of the outlet opening.
 8. A vesselimplant in accordance with claim 1, characterized in that the body isprovided with blood-permeable fixing means for the end of the body atthe outlet opening side, said fixing means being designed for contactwith the vessel wall of the blood vessel.
 9. A vessel implant inaccordance with claim 8, characterized in that the fixing means aredesigned to hold the body spaced apart from the vessel wall of the bloodvessel in the region of the outlet opening
 10. A vessel implant inaccordance with claim 8, characterized in that the fixing means areprovided at the body in the region of the outlet opening.
 11. A vesselimplant in accordance with claim 8, characterized in that the fixingmeans are made as a mesh, as a plurality of fixing elements respectivelyprojecting from the body with a radial component and/or as a conicalstent.
 12. A vessel implant in accordance with claim 8, characterized inthat the body or a part thereof is made in one piece with the fixingmeans.
 13. A vessel implant in accordance with claim 1, characterized inthat the wall of the body is rigid, flexible or partly rigid and partlyflexible.
 14. A vessel implant in accordance with claim 1, characterizedin that the vessel implant, in particular the body or the wall of thebody, is made in multiple parts.
 15. A vessel implant in accordance withclaim 1 having a first body in combination with a second said vesselimplant having a second body, said first and second bodies beingconnected to one another at a branch of the vessel implant in the regionof their respective entry openings.
 16. A vessel implant in accordancewith claim 15, characterized in that the two bodies have a commonsection adjoining the branch for contact with the vessel wall of theblood vessel.